Paper trim and dust must be collected and discarded in many paper handling systems. For example, high speed computer printers have tractor feeders that engage the tractor drive strips at the outer edges of a continuous web of paper. In post-processing equipment, the tractor drive strips are often trimmed away from the paper web. These paper strips are then thrown out or recycled. In addition, paper dust is generated as the strips of paper are trimmed. This dust should also be collected and discarded so that the operators do not breath the dust, and the dust does not coat the printer and post-processing area.
Previously, the collection of paper trim strip's was usually done manually by the operator who picked the trim off the floor. An example of an automatic trim rewinder is shown in U.S. Pat. No. 4,572,496, entitled "Trim Rewinder With Automatic Stop" and issued to Mark Casper and Robert Thomson on Feb. 25, 1986. However, the rewinder disclosed in the '496 Patent has no means to collect dust, requires a pressure plate to compact the baled trim, and the rewinder is rotatably fixed with respect to paper drum.
In the present invention, after the paper trim strips are mechanically trimmed from the paper web, the strips and associated dust fall into a funnel beneath the trimmer. A vacuum hose connected to the bottom of the funnel draws the trim strips and dust from the funnel and passes them into a cylindrical drum.
In the drum is a rewinder having a pair of rotating tines. These tines catch the paper strips and spin the strips into a paper bale. Initially, the rewinder tines are near the bottom of the drum so that the rotating paper bale is compacted as it is dragged against the drum bottom by the rotating tines. As the paper bale increases in size, the rewinder moves upward toward the center of the drum to allow more of the paper trim strips to be wound onto the bale. When the rewinder reaches the center of the drum, the paper bale fills the drum. At this point, the rewinder stops, the bale of paper is removed from the drum, and the bale is discarded or recycled.
The dust from the trimming operation is drawn by suction into the funnel through the hose and into the paper drum. The dust falls to the bottom of the drum into a dust trap. The dust falls to the bottom of the dust trap. Clean air is sucked out of the dust trap by a vacuum pump. The paper dust is discarded or recycled after being collected in the separator.
An electronic controller monitors the current load on the rewinder motor. The mechanical load on the rewinder increases as the paper bale expands and fills the space between the rewinder tines and the bottom of the drum. This increasing mechanical load increases the current load on the rewinder motor When the current load exceeds a threshold limit, the electronic controller triggers an elevator motor to move the rewinder towards the center of the drum. In this way, the controller automatically moves the rewinder to the center of the drum as the paper bale fills the drum.
One advantage of this invention is that it automatically removes and collects paper trim and dust. Another advantage of this invention is that its rewinder has fewer mechanical moving parts than prior rewinders. Furthermore, this invention advantageously adjusts the rewinder by monitoring current load. In addition, the invention is portable and can be easily adapted to a wide variety of printers and locations.